This application claims the priority of Japanese patent application 8-326814, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a starter motor and, in particular, to a starter motor for starting an internal combustion engine in which using a holder washer member a movement in an axial direction of an armature of the starter motor is regulated.
Conventional techniques relating to aforementioned type of starter motor are disclosed, for example, Japanese patent laid open publication No. Sho 63-309,767 and Japanese patent laid open publication No. Hei 7-310,631.
In the former document, a holder washer member for relating a movement of a motor shaft is sandwiched through a holder plate member and a rear bracket, and further the holder plate member is fixed to the rear bracket using a fastening screw member. The holder washer member is then fixed.
Further, by fastening a through bolt which penetrates through the rear bracket in an axial direction, the rear bracket and a yoke are fixed to a front bracket which supports a pinion shaft of the starter motor.
On the other hand, the second mentioned document involves a holder washer member itself, however a manner for fastening the holder washer member is the same as that of the first mentioned document.
In general, the size of an armature of a starter motor for starting an internal combustion engine is set in response to a required performance (a torque and a rotation number). In a case where the armature has a large size and a mass of the armature becomes large, in response to those situations, the through bolt is made larger.
Further, in this case, in accordance with a vibration from an outside portion or a vibration of the armature itself, since a force for moving the armature in an axial direction becomes larger, also naturally a force added to the holder washer member becomes larger.
As a result, in the above stated conventional starter motor structures in which the screw member for fixing the holder plate member is necessary, it is necessary to provide a larger screw member many screw members, etc.
As a result, component cost and a manufacturing cost of the motor increase remarkably.
An object of the present invention is to solve the above stated various problems and to provide a starter motor in which a holder washer member is sandwiched through a holder plate member and a rear bracket, wherein without use of a fixing component such as a screw member, the holder plate member can be fixed to the rear bracket.
The above stated object is attained according to a starter motor comprising an armature having a motor shaft in which a circumferential direction groove is formed at a vicinity of an end portion and a commutator which is fixed to the motor shaft, a rear bracket for rotatively supporting the end portion of the motor shaft, a cylindrical shape yoke in which one side opening end of the yoke is fitted into the rear bracket and another side opening end of the yoke supports one of the motor shaft and a pinion shaft, a holder washer member which is inserted in the groove of the motor shaft and limits a movement in an axial direction of the armature, and a brush holder member for holding a brush member which slides in the commutator and is fixed to a holder plate member.
In the above stated starter motor, the holder washer member is sandwiched between an inner side portion in a radial direction of the rear bracket and an inner side portion in a radial direction of the holder plate member, an outer peripheral edge portion of the holder plate member is sandwiched between an outer peripheral edge portion of the rear bracket and one end of the yoke, and the rear bracket is fixed through an installing bolt which penetrates through in an axial direction of the rear bracket.
It is preferable to provide the starter motor in which the installing bolt is fastened and fixed to the front bracket through a through bolt which penetrates through in the axial direction of the rear bracket.
It is preferable to provide the starter motor in which the outer peripheral edge portion of the rear bracket is formed with a flat plate shape, a step portion is provided to the one end of the yoke, and the flat plate shape outer peripheral edge portion of the rear bracket and the outer peripheral edge portion of the holder plate member are installed to the step portion.
In the present invention, first of all, the outer peripheral edge portion of the holder plate member is sandwiched between one opening end of the yoke and the outer peripheral edge portion of the rear bracket and another opening end is fitted into the front bracket of the starter motor.
Accordingly, when the rear bracket is fixed by fastening the through bolt, since an axial force of the through bolt is acted on the holder plate member through the rear bracket and the yoke, the holder plate member is strongly fixed to the rear bracket.
And this time, since the holder washer member is sandwiched between the inner side portion in the radial direction of the holder plate member and the inner side portion in the radial direction of the rear bracket, the holder plate member is strongly fixed to the rear bracket.